Synthesis mechanism of SiC–SiO2 core/shell nanowires grown by chemical vapor deposition

Abstract

Abstract Core–shell SiC–SiO2 nanowires were grown on silicon substrate with the chemical vapor deposition method using iron nitrate as promoter for the growth and CO as a carbon precursor, under atmospheric pressure and at a temperature of 1100 °C. The whole process involves two main stages: promoter conditioning (dewetting) and growth, by reaction with CO. The dewetting phase has been characterized by SEM and TEM techniques, x-ray diffraction and Raman spectroscopy. The results show that at the operating temperature, a solid-state reaction between the substrate and the promoter takes place with the formation of α-FeSi2. The growth of the nanowires begins after an induction time of about 5 min from the introduction of CO. The experimental data have been interpreted by considering a nucleation process involving a reaction between FeSi2 and CO. For the nanowires growth phase, a mechanism based on the Vapor-Liquid-Solid theory is proposed, compatible with the morphology of the drop-shaped particles present on the tip of the nanowires.